Housing
What size is your tank? 6.6 gallons (24" long x 8" wide x 9" deep)
What temperature is your tank? 80 F
Does your tank have a filter? Yes, set to low flow
Does your tank have an air stone or other type of aeration? No
Is your tank heated? Yes, keeps tank at constant temp of 80
What tank mates does your betta fish live with? None

Food
What type of food do you feed your betta fish? Aqueon Betta Food Pellets
How often do you feed your betta fish? 1-2 pellets in am and sometimes 1-2 in pm but not always, sometimes only in am. I soak his pellets in a small bowl of tank water for a couple mins first as he's had issues with swim bladder disease and this seems to help.

Maintenance
How often do you perform a water change? Every Saturday
What percentage of the water do you change when you perform a water change? about 33% (2 gallons)
What type of additives do you add to the water when you perform a water change? Prime and today Betta plus

Water Parameters:
Have you tested your water? Yes with API Master test kit.
If so, what are the following parameters?

Symptoms and Treatment
How has your betta fish's appearance changed? Shredded fins, red streaks in fins, red rash like marks on head.
How has your betta fish's behavior changed? None, very active, still swims over and "dances" around in front of me whenever I get near the tank. Very friendly, always hungry, follows fingers etc..
When did you start noticing the symptoms? Shredded fins about a month, red streaks about a week.
Have you started treating your fish? If so, how? I put him in one gallon hosp tank with just air stone and live plant for him to sit/hide on. Treated with tetrscycline (4 doeses over 4 days) Today moved him back to his regular tank.
Does your fish have any history of being ill? Had swim bladder disorder when I first got him, but we seem to have gotten over that by doing the pea, fast, pea thing... now only give him pellets that have been soaked in his fish water first. I always feed in one at a time and watch him eat it, there is no excessive food waste. I also know not to overfeed.
How old is your fish (approximately)? I'm pretty sure he was full grown when I got him at petco in early April of this year.

I finally got him over the whole swim bladder mess... then his tail started to shred..now he's getting these red lines in his fins and red on his head.

I know all of these things, swim bladder, fin rot and septicemia are all caused by dirty water or poor water conditions but I swear I test and change his water every week. I bought 2 one gallon jugs of water at the store because I wanted to use containers that had never had anything but water in them. I drank the water from the jugs and now use them for Gandalf's fish tank. Fri night, I fill the jugs with tapwater, then add the water conditioner and let it sit over night. Sat I scoop Gandalf out with his cup he came in, put the cover on and the remove approximately 2 gallons of water, I turn the filter on hi, and stir up all the gravel with a plastic spoon. Then I add the water from the jugs back to the tank, let it all settle and get back to the correct temp and let Gandalf float in his cup. After about 20 mins, I turn the filter back to low flow and release Gandalf.

Anyway...I can give you a lot more history if you need it but I'd like to get you guys opion on whether or not you think Gandalf has Septicemia based on these pictures.

The first picture was taken in April, The second picture taken today. :( I feel like such a bad parent!

Mainly commenting to bump this thread, I have no real clue what's going on here..

Just.. it is a bit odd he's not acting very sick? Though idk if that happens with septicemia.. all I can think of otherwise is that he's scraping himself and his fins on something rough in the tank, an ornament or plastic plant with sharp bits.

This is definitely him coming into his coloring... looks like you have a readhead!
I have a female who's coloring changes from day to day and she has the same spots your guy does.
Don't 4be surprised if you end up with a multi :)

Thank you everyone! I think it is just coloring, he still acts fine. I am going to get some aquarium salt though and try to address his fins. Do I need to remove the charcoal filter if I do the salt?

Also I'm in the process of trying to get my tank to cycle so I've increased the water changes 50% or so every 2-3 days. I've been taking everything out, decorations, plant, Gandalf, removing about 50 % of the water then turning the filter on high flow ( it's usually on low flow) and stirring up the gravel. Then after it all settles again i add the new treated water, put everything back in and float Gandalf in his cup until his water in his tank gets back to 80 again. Is this a good way to do it or should I be doing something else? Will the salt treatment "mess up" me trying to cycle the tank?